1 // Copyright 2015 The Servo Project Developers. See the
2 // COPYRIGHT file at the top-level directory of this distribution.
3 //
4 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
5 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
7 // option. This file may not be copied, modified, or distributed
8 // except according to those terms.
9
10 //! This module holds deprecated assets only.
11
12 use alloc::vec::Vec;
13
14 use super::*;
15
16 /// Find the level runs within a line and return them in visual order.
17 ///
18 /// NOTE: This implementation is incomplete. The algorithm needs information about the text,
19 /// including original `BidiClass` property of each character, to be able to perform correctly.
20 /// Please see [`BidiInfo::visual_runs()`](../struct.BidiInfo.html#method.visual_runs) for the
21 /// improved implementation.
22 ///
23 /// `line` is a range of bytes indices within `levels`.
24 ///
25 /// <http://www.unicode.org/reports/tr9/#Reordering_Resolved_Levels>
26 #[deprecated(since = "0.3.0", note = "please use `BidiInfo::visual_runs()` instead.")]
visual_runs(line: Range<usize>, levels: &[Level]) -> Vec<LevelRun>27 pub fn visual_runs(line: Range<usize>, levels: &[Level]) -> Vec<LevelRun> {
28 assert!(line.start <= levels.len());
29 assert!(line.end <= levels.len());
30
31 let mut runs = Vec::new();
32
33 // Find consecutive level runs.
34 let mut start = line.start;
35 let mut run_level = levels[start];
36 let mut min_level = run_level;
37 let mut max_level = run_level;
38
39 for (i, &new_level) in levels.iter().enumerate().take(line.end).skip(start + 1) {
40 if new_level != run_level {
41 // End of the previous run, start of a new one.
42 runs.push(start..i);
43 start = i;
44 run_level = new_level;
45
46 min_level = min(run_level, min_level);
47 max_level = max(run_level, max_level);
48 }
49 }
50 runs.push(start..line.end);
51
52 let run_count = runs.len();
53
54 // Re-order the odd runs.
55 // <http://www.unicode.org/reports/tr9/#L2>
56
57 // Stop at the lowest *odd* level.
58 min_level = min_level.new_lowest_ge_rtl().expect("Level error");
59
60 while max_level >= min_level {
61 // Look for the start of a sequence of consecutive runs of max_level or higher.
62 let mut seq_start = 0;
63 while seq_start < run_count {
64 if levels[runs[seq_start].start] < max_level {
65 seq_start += 1;
66 continue;
67 }
68
69 // Found the start of a sequence. Now find the end.
70 let mut seq_end = seq_start + 1;
71 while seq_end < run_count {
72 if levels[runs[seq_end].start] < max_level {
73 break;
74 }
75 seq_end += 1;
76 }
77
78 // Reverse the runs within this sequence.
79 runs[seq_start..seq_end].reverse();
80
81 seq_start = seq_end;
82 }
83 max_level.lower(1).expect(
84 "Lowering embedding level below zero",
85 );
86 }
87
88 runs
89 }
90